fix(codex): preserve responses api semantics (PR #436)

Fix Codex Responses API compatibility when requests pass through the
Anthropic adapter. The adapter was dropping Codex-specific request
fields and Responses Lite tool definitions during translation, and
Codex-native SSE responses containing custom tool calls were being
incorrectly routed through the Anthropic stream translator.

Co-authored-by: Morton Jonuschat <mjonuschat@gmail.com>